The present invention relates to road-sweeping machines and, more particularly, to road-sweeping machines designed to sweep debris of varying size, including vehicle tires and fragments thereof, from road surfaces.
Common highway debris includes consumer packaging, bottles, cans, and paper and plastic materials. Additionally, common road debris includes fragments of automobile and truck tires that are left on the road surface because of accident, delamination and fragmentation of re-treaded tires, blowouts, and similar misadventures. The tire fragments can include long strips of delaminated tread, rubber "chunks" of varying size, portions of the sidewall, irregularly shaped and sized portions of the bead and sidewall, and fragments with a multitude thin steel strands extending from the rubber compound. Occasionally, intact passenger car and truck tires are intentionally discarded on the roadway surface.
Highway debris is unsightly and, in the case of tires and tire fragments, an acknowledged road hazard. The governmental agencies responsible for highway maintenance have developed various strategies for the collection of highway debris. At the most basic level of maintenance, collection trucks and their crews patrol assigned areas with the crews manually picking-up and removing larger pieces of debris. As can be appreciated, the crews and their vehicles are exposed to on-going traffic as part of their work, and the capital and labor costs associated with debris collection can be relatively high in view of the amount of material that is collected.
Various types of machines have been designed to remove debris from roadways used by motor vehicles. In general, these designs include machines that can be towed behind a truck and designs that include their own engine and drive train. Many prior designs use some type of cylindrical brush that engages the road surface and which is rotated to brush road debris from the road surface onto a conveyor for delivery into a receptacle. In some cases, a second conveyor belt confronts the debris-carrying belt to effectively capture the debris between the two belts as it is transported to the debris receptacle.
In general, prior art road sweepers are reasonably effective in removing smaller, lightweight debris that falls below a recognized size and weight limit, such debris being represented by bottles, cans, paper goods, and plastics. However, prior art machines are generally not adept at sweeping large irregularly shaped debris, such as tire fragments, or entire tires, from the road surface. Tire fragments and tires represent a particular problem since the debris can vary in size from a few centimeters to a meter or more and can vary in weight from a few ounces to many pounds (in the case of an intact truck tire). Additionally, many tire fragments do not have a substantial shape-sustaining characteristic, for example, long strip-like sections of delaminated treads. Lastly, any high-strength steel strands in the bead and in the tread portion of a tire fragment can interfere with the mechanical components of prior art sweepers.